Disconnection detection device, disconnection detection method, and connector for disconnection detection

Abstract

To provide a disconnection detection device, a disconnection detection method, and a connector for disconnection detection that can detect disconnection early.SOLUTION: A device detects disconnection of a wire in a plurality of insulating electric wires 101, and comprises: a branch part 6 that has a common conductive path 61 and a plurality of branching conductive paths 62 provided to branch from a leading end of the common conductive path 61, wherein one end of a conductor 102 of the corresponding insulating electric wire 101 is electrically connected to the leading end of each of the branching conductive paths 62; a current ratio detection unit 7 that can detect the ratio of currents flowing in the plurality of branching conductive paths 62; a current detection unit 8 that can detect the waveform of a current flowing in the common conductive path 61 or the branching conductive paths 62; a noise prevention processing unit 21 that performs noise prevention processing on the ratio of currents detected by the current ratio detection unit 7 on the basis of the waveform of the current detected by the current detection unit 8; and a disconnection detection processing unit 22 that detects disconnection of the wire in the plurality of insulating electric wires 101 on the basis of the ratio of currents on which the noise prevention processing is performed.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a wire break detection device, a wire break detection method, and a wire break detection connector. [Background technology]

[0002] In cables wired to moving parts of equipment such as industrial robots, repeated bending and twisting of the moving parts gradually causes the wires (metal wires such as copper wires) that make up the conductor to break, eventually leading to a break in the conductor. Therefore, it is desirable to detect a break in a wire and replace the cable before the entire conductor breaks.

[0003] When a wire that makes up a conductor breaks, the resistance of the conductor increases, so conventionally, wire breaks have been detected by measuring the resistance of the conductor. For example, the resistance of the conductor is measured in an initial state where no breaks have occurred, and when the resistance increases from the resistance in the initial state, a break in the wire is detected.

[0004] Prior art document information related to the invention of this application includes Patent Document 1. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-139488 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the case of early breaks, when the change in the conductor's resistance is small (mΩ or less) and the number of broken wires making up the conductor is small, the increase in the conductor's resistance is extremely small. Furthermore, because the resistivity of the conductor and the contact potential generated between the electrodes of a resistance measuring instrument and the conductor being measured vary with temperature, the resistance of the conductor also varies with temperature, making it difficult to detect a slight increase in resistance when the number of broken wires is small. Therefore, unless the number of broken wires making up the conductor increases (the resistance value increases by several tens of percent from the initial value), it is not possible to detect a break in a wire, making it difficult to detect early breaks.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a wire break detection device, a wire break detection method, and a wire break detection connector that are capable of detecting wire breaks at an early stage. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the present invention provides a device for detecting breaks in wires of a plurality of insulated electric wires having conductors made of a plurality of wires, the device comprising: a common conductive path and a plurality of branch conductive paths branching from a tip of the common conductive path, with one end of the conductor of a corresponding insulated electric wire being electrically connected to each tip of the branch conductive path; a current ratio detection unit capable of detecting a ratio of currents flowing through the plurality of branch conductive paths; a current detection unit capable of detecting the waveform of the current flowing through the common conductive path; a noise suppression processing unit that performs noise suppression processing on the ratio of the currents detected by the current ratio detection unit using the current waveforms detected by the current detection unit; and a break detection processing unit that detects breaks in the wires of the plurality of insulated electric wires based on the ratio of the currents after the noise suppression processing.

[0009] Furthermore, in order to solve the above-mentioned problems, the present invention provides a wire break detection device for detecting a wire break in a plurality of insulated wires having a conductor made up of a plurality of wires, the wire break detection device comprising: a current ratio detection unit capable of detecting a ratio of currents flowing through the plurality of insulated wires when current from a predetermined supply source is branched and supplied to the plurality of insulated wires; a current detection unit capable of detecting the waveform of the current from the supply source or the current flowing through the plurality of insulated wires; a noise suppression processing unit that performs noise suppression processing on the ratio of the currents detected by the current ratio detection unit based on the current waveforms detected by the current detection unit; and a wire break detection processing unit that detects a wire break in the plurality of insulated wires based on the ratio of the currents after the noise suppression processing.

[0010] Furthermore, in order to solve the above-mentioned problems, the present invention provides a method for detecting a break in a wire in a plurality of insulated wires having a conductor made up of a plurality of wires, the method comprising: detecting a ratio of currents flowing through the plurality of insulated wires when current from a predetermined supply source is branched and supplied to the plurality of insulated wires; detecting a waveform of the current from the supply source or the current flowing through the plurality of insulated wires; performing noise suppression processing on the detected current ratio based on the detected current waveform; and detecting a break in any of the wires in the plurality of insulated wires based on the ratio of the currents after the noise suppression processing.

[0011] Furthermore, in order to solve the above-mentioned problems, the present invention provides a connector for detecting wire breaks in a plurality of insulated electric wires having conductors each made of a plurality of wires, the connector having a common conductive path and a plurality of branch conductive paths arranged to branch off from the tip of the common conductive path, and including a branch portion to which one end of the conductor of a corresponding insulated electric wire is electrically connected at each tip of the branch conductive path, a current ratio detection unit capable of detecting the ratio of currents flowing through the plurality of branch conductive paths, and a current detection unit capable of detecting the waveform of the current flowing through the common conductive path or the current flowing through the branch conductive paths. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a wire break detection device, a wire break detection method, and a wire break detection connector that are capable of detecting wire breaks at an early stage. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic configuration diagram of a wire break detection device according to an embodiment of the present invention; [Figure 2] 1A is a perspective view of a connector for detecting disconnection according to one embodiment of the present invention, and FIG. 1B is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of a cable. [Figure 3] FIG. 2 is a plan view of a branching portion and a magnetic sensor. [Figure 4] 10(a) and 10(b) are diagrams illustrating detection of wire breakage. [Figure 5] 1A is a diagram showing an example of a waveform of the total current, FIG. 1B is a diagram showing the spectrum of the total current, and FIG. 1C is a diagram showing the square of the spectrum of the total current. [Figure 6] 1A is a diagram showing an example of a waveform of a current ratio when there is no disconnection, FIG. 1B is a diagram showing a spectrum of the current ratio, and FIG. 1C is a diagram showing a spectrum of the current ratio when a spectrum mask is applied. [Figure 7] 10A is a diagram showing an example of a waveform of a current ratio when there is a disconnection, and FIG. 10B is a diagram showing a spectrum of the current ratio when a spectrum mask is applied. [Figure 8] 1A is a flowchart of a disconnection detection method according to an embodiment of the present invention, and FIG. 1B is a flowchart of a noise suppression process. [Figure 9] FIG. 10 is a flow diagram of a disconnection detection process. [Figure 10] 10A and 10B are diagrams showing a modified example of the current detection section, in which (a) is a plan view and (b) is a cross-sectional view taken along line BB in (a). [Figure 11] 10(a) and 10(b) are diagrams illustrating noise suppression processing in another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] [Embodiment Mode] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0015] Fig. 1 is a schematic diagram of a wire break detection device 1 according to this embodiment. Fig. 2(a) is a perspective view of a connector (wire break detection connector) 13, and Fig. 2(b) is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of a cable 10.

[0016] The cable break detection device 1 is a device that detects whether a cable 10 wired to any device (managed device) 11 managed by an device user or device manufacturer is broken by the applied motion (bending, twisting, swinging, etc.) such as bending, twisting, swinging, etc., based on the operation of the device 11. For example, the device 11 has a movable part 11b, and the cable 10 is wired so as to pass through the movable part 11b. By operating the movable part 11b of the device 11, the cable 10 is repeatedly bent, twisted, swinging, etc., and the like. FIG. 1 illustrates a case where the device 11 to which the cable 10 is wired is an industrial robot 11a. However, the device 11 may also be a vehicle such as an automobile. Note that the cable 10 to be detected is not limited to a cable 10 wired to the device 11, but may also be a cable 10 removed from the device 11 or a cable 10 being considered for installation in the device 11 (for example, a stage of designing the wiring and specifications of the cable 10 to the device 11). Furthermore, the action applied to cable 10 may be an action such as bending that simulates the action that occurs when cable 10 is wired to device 11 and in operation, for example, an action such as bending that is applied to device 11 when performing maintenance on device 11, or an action such as bending that is applied when evaluating the specifications and characteristics of cable 10 when considering implementation in device 11.

[0017] Hereinafter, the term "breakage of a wire" refers to a breakage of each of the wires constituting the conductor 102 of the cable 10. Furthermore, the term "breakage progression state of the conductor 102" refers to the breakage rate, or the percentage of the wires constituting the conductor 102 that have broken due to repeated bending, twisting, swinging, and other movements of the cable 10. In other words, the number of broken wires among the wires constituting the conductor 102. The breakage progression state of the conductor 102 can be expressed as the ratio (%) of the number of broken wires to the total number of wires constituting the conductor 102. For example, a breakage rate of 100% indicates that all of the wires constituting the conductor 102 are broken. In other words, the breakage progression state of the conductor 102 can be said to be the breakage progression state of the cable 10.

[0018] Furthermore, "disconnection of the conductor 102" means that the percentage of wires that make up the conductor 102 that have broken has reached a preset percentage, reaching a state where it is determined that the conductor 102 has broken. For example, the state where it is determined that the conductor 102 has broken is set to when the resistance increase rate (the rate of increase in the resistance value of the conductor 102 relative to the initial resistance value of the conductor 102) of the conductor 102 that makes up the cable 10 exceeds 20%, and the percentage of wires that break (= the progress of the disconnection of the conductor 102) at this time is, for example, 80% or more. Disconnection of the conductor 102 is an indicator that the cable 10 has reached the end of its life and serves as a guide for recommending replacement of the cable 10. Therefore, the life of the cable 10 can be predicted by predicting when the conductor 102 will break.

[0019] A robot control device 12 for controlling the industrial robot 11a is connected to the industrial robot 11a. The robot control device 12 is equipped with an operation control unit 12a that controls the operation of the industrial robot 11a (operation of the movable part 11b). The robot control device 12 stores an operation program (not shown) that presets the order of operation of the movable part 11b, the angle of operation, speed, etc., and the operation control unit 12a operates the industrial robot 11a in accordance with the operation program.

[0020] (Disconnection detection device 1) The wire break detection device 1 is a device that detects breaks in wires in a plurality of insulated electric wires 101 having conductors 102 each made up of a plurality of wires. The wire break detection device 1 includes a connector (wire break detection connector) 13 and a computing device 100. The connector 13 is provided, for example, on the base 11c of the industrial robot 11a. At least a branching portion 6, a current ratio detecting portion 7, and a current detecting portion 8 are provided within the connector 13. The computing device 100 is provided separately from the industrial robot 11a. Note that the connector 13, which has at least the branching portion 6, the current ratio detecting portion 77, and the current detecting portion 8, may be provided in a portion that is connected to an end of a cable 10 for which wire breakage is to be detected. Therefore, the connector 13 may be provided in a portion of the industrial robot 11a other than the base 11c (for example, the movable portion 11b, etc.).

[0021] (Branch 6) The branch portion 6 has a common conductive path 61 and a plurality of branch conductive paths 62 (the same number as the insulated electric wires 101) branched from the tip of the common conductive path 61. One end of the conductor 102 of the corresponding insulated electric wire 101 is electrically connected to each tip of the branch conductive paths 62. This allows current supplied from the common conductive path 61 to be supplied to the plurality of insulated electric wires 101 via the plurality of branch conductive paths 62.

[0022] As shown in FIGS. 2(a) and 2(b), in this embodiment, there are two insulated electric wires 101 targeted for disconnection detection. However, this is not limited to this, and three or more insulated electric wires 101 may be targeted for disconnection detection. The cable 10 includes two insulated electric wires 101, each having an insulator 103 covering a conductor 102, and a sheath 104 covering the two insulated electric wires 101 collectively. The two insulated electric wires 101 preferably have the same configuration, and preferably have the same length, conductor cross-sectional area, and resistance value. The other ends of the two insulated electric wires 101 are connected to the same connection destination. In other words, between the connection destination of the cable 10 and the common conductive path 61, multiple (here, two) insulated electric wires 101 and branch conductive paths 62 connected in series are connected in parallel. In other words, the cable 10 can be said to be two insulated electric wires 101, each divided into two halves and covered with an insulator 103. The cable 10 may have a tape member or a shielding member that covers the periphery of the plurality of insulated wires 101 collectively.

[0023] In this embodiment, the branch portion 6 is formed of a bus bar, which is a plate-shaped conductive path, and is configured in a plate shape as a whole. The common conductive path 61 has a cross section perpendicular to the longitudinal direction formed in a substantially rectangular plate shape, and a bolt hole 61a is formed at its base end for bolting and electrically connecting the tip end of a cable (not shown) from the robot control device 12. The branch portion 6 has two branch conductive paths 62 at the tip end (the end opposite the base end) of the common conductive path 61, corresponding to the two insulated electric wires 101 for which disconnection detection is to be performed. As shown in FIGS. 2(a) and 3, the two branch conductive paths 62 have a cross section perpendicular to the longitudinal direction formed in a substantially rectangular plate shape, and are provided integrally with the common conductive path 61 so as to branch off from the tip end of the common conductive path 61 in a substantially Y-shape in plan view. Both branch conductive paths 62 are formed to extend along the long side direction of the common conductive path 61, and bolt holes 62a are formed at the tip ends of both branch conductive paths 62 for bolting terminals 105 provided at the tip ends of the insulated electric wires 101, so that the tip ends of both branch conductive paths 62 are electrically connected to the tip ends of the conductors 102 of the insulated electric wires 101. The two branch conductive paths 62 are formed to have the same shape, and are configured to have the same cross-sectional area, cross-sectional shape, planar shape, and resistance value. As shown in FIG. 3 , in a plan view, the branch portions 6 are formed to be line-symmetrical with respect to a central axis O passing through the center of the common conductive path 61.

[0024] The specific shape of the branch portion 6 can be changed as appropriate. For example, the branch portion 6 does not have to be plate-shaped, and its cross-sectional shape may be circular, elliptical, polygonal, or the like. By providing the branch portion 6, current from a predetermined supply source (here, the robot control device 12) is divided and supplied to a plurality of (here, two) insulated electric wires 101. Here, the two insulated electric wires 101 have the same configuration and are connected to the same connection destination. Therefore, when neither insulated electric wire 101 is broken, the current from the robot control device 12 is divided and supplied evenly to the two insulated electric wires 101.

[0025] (Current ratio detection unit 7) The current ratio detector 7 detects the ratio of the currents flowing through the branch conductive paths 62 (i.e., the ratio of the currents flowing through the insulated electric wires 101). In this embodiment, the current ratio detector 7 includes a magnetic sensor 71 disposed between the two branch conductive paths 62. The magnetic sensor 71 includes a magnetic detection element such as a Hall element or a GMR (Giant Magneto-Resistive effect) element. As shown in FIG. 3 , the magnetic sensor 71 is disposed such that its magnetic detection portion 71 a is located midway between the two branch conductive paths 62 (overlapping with the central axis O). To improve the accuracy of detecting a disconnection, the magnetic sensor 71 is preferably disposed such that its magnetic detection portion 71 a is located at the center of the branch portion 6 in the thickness and width directions. Furthermore, because magnetic field disturbances occur near the common conductive path 61 and at the ends of the branch conductive paths 62 (near the connection portions of the insulated electric wires 101), it is preferable to dispose the magnetic sensor 71 away from the common conductive path 61 and the ends of the branch conductive paths 62.

[0026] As shown in FIG. 4( a), when there is no wire break in either of the two insulated wires 101, the currents flowing through both branch conductive paths 62 are equal, and at the magnetic detection unit 71a of the magnetic sensor 71, which is equidistant from both branch conductive paths 62, the magnetic fields generated by the currents flowing through both branch conductive paths 62 cancel each other out. Therefore, the magnetic field strength detected by the magnetic sensor 71 is zero. In other words, when there is no wire break in either of the two insulated wires 101, the ratio of the currents flowing through both branch conductive paths 62 remains almost unchanged from the initial state, and the magnetic field strength detected by the magnetic sensor 71 also remains almost unchanged from the initial state. Therefore, it is possible to detect that there is no wire break in either of the two insulated wires 101 based on the sensor output of the magnetic sensor 71.

[0027] On the other hand, as shown in FIG. 4( b), if a wire breakage occurs in one of the insulated wires 101, the resistance of the conductor 102 in the insulated wire 101 where the wire breakage occurs increases slightly, resulting in a difference in the currents flowing through the two branch conductive paths 62. As a result, a difference occurs in the magnetic field generated at the magnetic detection unit 71a of the magnetic sensor 71 by the currents flowing through the two branch conductive paths 62, and the magnetic field strength (absolute value of the magnetic field strength) detected by the magnetic sensor 71 increases. In other words, when a wire breakage occurs in at least one of the two insulated wires 101, the ratio of the currents flowing through the two branch conductive paths 62 changes from the initial state, and the magnetic field strength detected by the magnetic sensor 71 also changes from the initial state. Therefore, it is possible to detect a wire breakage in one of the two insulated wires 101 based on the sensor output of the magnetic sensor 71.

[0028] Returning to FIG. 2(a), the magnetic sensor 71, which is the current ratio detection unit 7, is mounted on a circuit board 131. The circuit board 131 and the branching portion 6 are arranged so as to overlap in the thickness direction. The circuit board 131 and the branching portion 6 are fixed to each other by a resin fixing member 132 having a clamping portion 132a that clamps the common conductive path 61 in the width direction and a fixing portion 132b that is fixed to the back surface of the circuit board 131. The circuit board 131 is equipped with a circuit that performs signal processing of the magnetic sensor 71 and is also provided with a connector portion 131a that is used to output the sensor output of the magnetic sensor 71. The sensor output output from the connector portion 131a is input to the arithmetic device 100. Shielding plates 133 are provided on the front and back surfaces of the circuit board 131 via spacers 131b to prevent external magnetic fields from affecting the magnetic sensor 71. Note that in FIG. 2(a), the upper shielding plate 133 is indicated by a dashed line.

[0029] In this embodiment, the magnetic sensor 71 is mounted on the circuit board 131, but the magnetic sensor 71 does not have to be mounted on the circuit board 131. For example, a structure may be used in which a lead frame is punched at a predetermined position, the magnetic sensor 71 is disposed in the punched portion, and the lead frame and the magnetic sensor 71 are connected by wire bonding or the like.

[0030] Furthermore, in this embodiment, the magnetic sensor 71 is used as the current ratio detector 7, but the current ratio detector 7 is not limited to the magnetic sensor 71 and may be any sensor that can directly detect the ratio (proportion) of the currents flowing through both branched conductive paths 62. For example, the current ratio detector 7 may be configured by an ammeter provided between both branched conductive paths 62.

[0031] However, the change in the current ratio detected by the current ratio detector 7 due to a wire break is slight, and the fluctuation in the magnetic field detected by the magnetic sensor 71 is also very small. Therefore, even if the shield plate 133 is provided, the magnetic sensor 71 may detect an external magnetic field as noise, and may determine that a wire break has occurred in the two insulated electric wires 101 even though no wire break has occurred. In particular, when the branch portion 6 and the current ratio detector 7 are provided near a circuit board or the like with high wiring density, it may be difficult to eliminate magnetic interference that causes noise, and measures to prevent noise are desired. Therefore, in this embodiment, focusing on the fact that the current flowing through the common conductive path 61 is relatively large and can increase the signal-to-noise ratio, noise suppression processing is performed using the current flowing through the common conductive path 61. Details of the noise suppression processing will be described later.

[0032] (Current detection unit 8) The current detection unit 8 detects the waveform of the current flowing through the common conductive path 61. The current waveform detected by the current detection unit 8 is used for noise suppression processing, which will be described later. In this embodiment, the current detection unit 8 is made up of a CT (Current Transformer) sensor having a coil 81 formed by winding a conductor around the common conductive path 61, and an ammeter 82 that measures the induced current generated in the coil 81 by the current flowing through the common conductive path 61. Hereinafter, the current flowing through the common conductive path 61 will be referred to as the total current.

[0033] The current detection unit 8 is not limited to a CT sensor and may have any configuration as long as it can detect the waveform of the total current. For example, if a control circuit or the like (here, the robot control device 12) is connected to the common conductive path 61 side, the current detection unit 8 may be configured to detect the waveform of the total current using the current monitor output of the control circuit or the like (here, the robot control device 12). Also, the current detection unit 8 may be configured by a magnetic sensor provided near the common conductive path 61.

[0034] (Arithmetic unit 100) The arithmetic device 100 includes a control unit 2 and a storage unit 3. A display unit 4 is connected to the disconnection detection device 1, and various information, such as the results of disconnection detection, can be displayed on the display unit 4. The disconnection detection device 1 is also provided with an input device 5, such as a keyboard, so that various settings and the display contents of the display unit 4 can be operated by inputting information from the input device 5. The display unit 4 may be configured as a touch panel display so that it also functions as the input device 5. The display unit 4 and the input device 5 do not need to be connected to the disconnection detection device 1 by wire, but may be connected wirelessly. In this case, the display unit 4 and the input device 5 may be, for example, a smartphone or a tablet. The arithmetic device 100 may also be provided as a calculation unit within the robot control device 12.

[0035] The control unit 2 has a data acquisition processing unit 20, a noise suppression processing unit 21, a disconnection detection processing unit 22, and a cable life prediction processing unit 23. The data acquisition processing unit 20, the noise suppression processing unit 21, the disconnection detection processing unit 22, and the cable life prediction processing unit 23 are realized by appropriately combining a processing element such as a CPU, a memory such as a RAM or a ROM, software, an interface, a storage device, and the like.

[0036] (Data acquisition processing unit 20) The data acquisition processing unit 20 performs data acquisition processing to acquire the sensor output of the magnetic sensor 71, which is the current ratio detection unit 7, and the sensor output from the CT sensor, which is the current detection unit 8. The data acquisition processing unit 20 stores the acquired sensor outputs of the current ratio detection unit 7 and the current detection unit 8 in the memory unit 3 as sensor output data 31.

[0037] (Noise suppression processing unit 21) The noise suppression processing unit 21 performs noise suppression processing of the current ratio detected by the current ratio detection unit 7 based on the waveform of the total current detected by the current detection unit 8. In this embodiment, the noise suppression processing unit 21 performs noise suppression processing by applying the spectrum of the total current detected by the current detection unit 8 as a spectrum mask to the spectrum of the current ratio.

[0038] As an example, consider the case where a PWM (Pulse Width Modulation) signal such as that shown in FIG. 5(a) is input to the common conductive path 61. The current detection unit 8 detects the waveform shown in FIG. 5(a) as the total current waveform. The noise suppression processing unit 21 performs frequency analysis of the total current waveform detected by the current detection unit 8 to calculate the total current spectrum. FIG. 5(b) shows the total current spectrum calculated from the total current waveform in FIG. 5(a). The total current has a relatively large current value, and the noise component is relatively small compared to the current value flowing through the branch conductive path 62 (high S / N ratio). Therefore, in this embodiment, the total current spectrum, which is less affected by noise, is used as the spectrum mask. Note that the total current spectrum may be processed in a predetermined manner (e.g., by setting the signal strength to zero when the signal strength is less than a predetermined value) and the processed spectrum may be used as the spectrum mask. FIG. 5(c) shows the result of squaring the signal strength at each frequency in the total current spectrum. FIG. 5(c) is used in the disconnection detection process described later.

[0039] FIG. 6(a) shows the waveform of the sensor output (current ratio waveform) of the magnetic sensor 71 when there is no break in the insulated wire 101. This figure shows the case where noise with a frequency approximately 10% higher than the PWM modulation frequency of the total current and white noise are added. The noise suppression processing unit 21 performs frequency analysis on the current ratio waveform (here, the sensor output of the magnetic sensor 71) detected by the current ratio detection unit 7 to determine the current ratio spectrum. The current ratio spectrum determined from the current ratio waveform of FIG. 6(a) is shown in FIG. 6(b).

[0040] The noise suppression processing unit 21 then applies a spectrum mask to the obtained current ratio spectrum. More specifically, the noise suppression processing unit 21 performs a process of multiplying the spectrum mask (the total current spectrum in FIG. 5(b)) by the signal strengths of the same frequencies in the current ratio spectrum in FIG. 6(b). FIG. 6(c) shows the result of applying the total current spectrum in FIG. 5(b) as a spectrum mask to the current ratio spectrum in FIG. 6(b). As shown in FIG. 6(c), when there is no break in the insulated wire 101, the current ratio spectrum after the spectrum mask is applied is in a state in which frequency components that are not present in the total current are cut and noise is suppressed, and the signal strength of each frequency is close to zero.

[0041] FIG. 7(a) shows the waveform (current ratio waveform) of the sensor output of the magnetic sensor 71 when a break occurs in the insulated wire 101. The spectrum of this current ratio waveform was calculated, and the result of applying a spectrum mask is shown in FIG. 7(b). As shown in FIG. 7(b), when there is a break in the insulated wire 101, only frequency components common to the total current remain. The magnitude of the current ratio when a break occurs changes in sync with the magnitude of the total current. Therefore, as can be seen by comparing FIG. 6(c) with FIG. 7(b), it is possible to clearly determine whether there is a break from the spectrum of the current ratio after applying the spectrum mask.

[0042] (Disconnection detection processing unit 22) The disconnection detection processing unit 22 performs a disconnection detection process to detect disconnections in the wires of multiple (here, two) insulated electric wires 101 based on the ratio of currents that have been subjected to noise suppression processing, i.e., the spectrum of the ratio of currents to which a spectrum mask has been applied (see Figures 6(c) and 7(b)).

[0043] More specifically, if there is a frequency where the signal strength is greater than a predetermined threshold in the spectrum of the current ratio to which the spectrum mask has been applied (see Figures 6(c) and 7(b)), it is possible to detect a break in the wire. However, in this case, there is a risk of erroneous detection if a large amount of noise is momentarily input to the magnetic sensor 71. Therefore, in this embodiment, multiple frequencies with large signal strength (frequencies where the signal strength peaks) are selected from the spectrum of the current ratio to which noise suppression processing has been performed (to which the spectrum mask has been applied), and the relative ratio of the signal strengths at the selected frequencies is calculated. If the calculated relative ratio of the signal strengths is within a predetermined threshold range, a break in the wire is detected.

[0044] Here, the threshold range may be determined based on the waveform (spectrum) of the total current. For example, it can be set based on the relative ratio of signal strength at a selected frequency in the spectrum of the total current to which a spectrum mask is applied (i.e., the square of the spectrum of the total current shown in Figure 5(c)) (for example, within a threshold range of ±10%). If the waveform of the total current is constant, the threshold range can also be set in advance taking the waveform of the total current into consideration. This makes it possible to detect a wire break when the relative ratio of signal strength when the spectrum mask is applied nearly matches the ratio of the total current to the current, thereby making it possible to suppress false detections when, for example, a large amount of noise is momentarily input.

[0045] The disconnection detection processing unit 22 may issue an alarm when detecting a disconnection of the wire. The disconnection detection processing unit 22 stores the result of the disconnection detection (determination result) in the storage unit 3 as disconnection detection data 32.

[0046] Note that the greater the number of wire breaks, i.e., the more the break progresses, the greater the signal strength in the spectrum of the current ratio after noise suppression (with spectrum mask applied). Therefore, the break detection processing unit 22 may be configured to detect the progress of the break in the conductor 102 based on the signal strength in the spectrum of the current ratio after noise suppression (with spectrum mask applied). When detecting the progress of the break in the conductor 102, thresholds for the signal strength are set in stages in advance, and when the value of the signal strength exceeds the set threshold, it is possible to detect that the break in the conductor 102 is progressing.

[0047] (Cable life prediction processing unit 23) The cable life prediction processor 23 performs a cable life prediction process to predict the time until the conductor 102 breaks, i.e., the time until the cable 10 reaches the end of its life (hereinafter referred to as the cable life), based on the ratio of the currents after the noise suppression process. The cable life prediction processor 23 may predict how much time will pass from the present until the cable reaches its end of its life, based on, for example, the period (or the number of operations) from the start of use of the cable 10 until an initial break or a predetermined break progression state occurs. The prediction result of the cable life prediction process is stored in the storage unit 3 as life prediction data 33. Note that the cable life prediction processor 23 is not essential and can be omitted.

[0048] (Disconnection detection method) FIG. 8(a) is a flow diagram of a wire break detection method according to this embodiment. The flow in FIG. 8(a) is started, for example, when the device 11 starts operating or when the cable 10 starts to be bent. As shown in FIG. 8(a), first, in step S1, the data acquisition processing unit 20 starts acquiring sensor output data from the current ratio detection unit 7 (magnetic sensor 71) and the current detection unit 8. The acquired sensor output data is stored in the storage unit 3 as sensor output data 31. The sensor output data may be acquired continuously throughout the entire period during which the device 11 is operating or during which the cable 10 is being bent, or may be acquired at predetermined intervals. Furthermore, the sensor output data may be acquired during periods during which the device 11 is not operating, such as during maintenance work, by bending the cable 10. By acquiring the sensor output data during the period during which the device 11 is operating, the progression of a wire break in the conductor 102 can be detected according to the operating state of the device 11.

[0049] Then, in step S2, noise suppression processing is performed. In the noise suppression processing, as shown in Fig. 8(b), first, in step S21, the spectrum of the total current is obtained based on the sensor output of the current detection unit 8, and the spectrum of the current ratio is obtained based on the sensor output of the current ratio detection unit 7 (magnetic sensor 71). Then, in step S22, the spectrum of the total current is applied as a spectrum mask to the spectrum of the current ratio (by multiplying the signal strengths of the same frequencies) to obtain a spectrum of the current ratio that has been subjected to noise suppression processing. Then, the process returns and proceeds to step S3 in Fig. 8(a).

[0050] In step S3, a disconnection detection process is performed. In the disconnection detection process, as shown in FIG. 9, first, in step S31, it is determined whether a signal strength higher than a set threshold exists in the spectrum of the current ratio after noise suppression processing. If the determination in step S31 is No (N), the process proceeds to step S36. If the determination in step S31 is Yes (Y), in step S32, multiple frequencies with high signal strength are selected in the spectrum of the current ratio after noise suppression processing, and the relative ratio of the signal strengths is calculated. Thereafter, in step S33, in the spectrum obtained by applying a spectrum mask to the spectrum of the total current (i.e., by squaring the signal strength of each frequency), the relative ratio of the signal strengths at the frequencies selected in step S32 is calculated. Thereafter, in step S34, it is determined whether the relative ratio of the signal strengths calculated in step S32 is within ±10 of the relative ratio of the signal strengths calculated in step S33. Note that the value of "±10%" in step S34 is just an example and can be changed as appropriate. If the determination in step S34 is No (N), the process proceeds to step S36. If the determination in step S34 is Yes (Y), the process in step S35 determines that there is a wire break in one of the insulated wires 101, and stores the determination result in the memory unit 3 as wire break detection data 32. Thereafter, the process returns and proceeds to step S4 in FIG. 8(a). In step S36, it determines that there is no wire break in both insulated wires 101, and stores the determination result in the memory unit 3 as wire break detection data 32. Thereafter, the process returns and proceeds to step S4 in FIG. 8(a).

[0051] Although not shown, in the wire breakage detection process, the result of the wire breakage detection may be displayed on the display 4, and an alert may be issued when a wire breakage is detected. Furthermore, the wire breakage detection data 32 obtained in the wire breakage detection process may be used to acquire other data for managing the state of the cable 10. For example, the robot control device 12 may be configured to perform an imaging process in which, based on the wire breakage detection data 32, a camera or the like starts capturing images of the operating status of the cable 10 wired to the industrial robot 11a, and the captured data (image data) for a predetermined period is stored in the storage unit 3 of the robot control device 12 or the computing device 100. The image data stored in the storage unit 3 can be used to stop the operation of the industrial robot 11a or replace the cable 10.

[0052] In step S4, it is determined whether the operation of the device 11 has ended. If the determination in step S4 is NO, the process returns to step S2. If the determination in step S4 is YES, in step S5, data acquisition by the data acquisition processing unit 20 is completed, and then the process ends. Although not shown in the figure, a cable life prediction process may be performed after step S5.

[0053] (Variation) In this embodiment, the current detection unit 8 is configured with a CT sensor, but is not limited to this. As shown in FIGS. 10(a) and 10(b), the current detection unit 8 may be configured with two second magnetic sensors 83 arranged near both branch conductive paths 62. Here, the second magnetic sensors 83 are arranged to face the magnetic sensor 71 across the branch conductive path 62. In this case, the magnetic fields detected by the two second magnetic sensors 83 are in opposite directions. Therefore, by calculating the difference between the sensor outputs of the two second magnetic sensors 83, it is possible to detect the total current while canceling the effects of noise from the two second magnetic sensors 83.

[0054] In addition, in this embodiment, the spectrum of the total current (the current flowing through the common conductive path 61) is used as the spectrum mask, but the spectrum of the current flowing through the branch conductive path 62 may also be used as the spectrum mask. In this case, the current detection unit 8 is configured to detect the waveform of the current flowing through the branch conductive path 62.

[0055] In addition, in this embodiment, the branch conductive paths 62 and the insulated wires 101 have the same configuration so that the currents flowing through the branch conductive paths 62 are equal, but this is not limiting, and the branch conductive paths 62 and the insulated wires 101 may have different configurations. In this case, the output of the magnetic sensor 71 will not be zero even when there is no break in the wire, but as described above, it is possible to detect a break in the wire based on the change in the sensor output relative to the normal state (the state before the break in the wire occurs).

[0056] In addition, in this embodiment, two insulated wires 101 are the targets of wire breakage detection, but the invention is not limited to this, and three or more insulated wires 101 may be the targets of wire breakage detection.

[0057] Furthermore, although not mentioned in this embodiment, it is also possible to detect a wire breakage taking into account the operating frequency of the movable part 11b of the device 11. When the movable part 11b operates while a wire breakage has occurred, the distance between the broken wires (the distance between the broken wires) expands or contracts in response to the operation, and the resistance value of the conductor 102 fluctuates in response to the operation of the movable part 11b. Therefore, it is possible to detect a wire breakage and the progression of the breakage in the conductor 102 based on the operating frequency component (or its higher-order frequency component) obtained by measuring the time-series change in the sensor output (the ratio of the currents flowing through both branched conductive paths 62) while the movable part 11b is operated at a constant cycle and performing frequency analysis on the measured sensor output.

[0058] (Actions and Effects of the Embodiments) As described above, the wire break detection device 1 of this embodiment has a common conductive path 61 and a plurality of branch conductive paths 62 branched from the tip of the common conductive path 61, and is equipped with a branch section 6 to which one end of the conductor 102 of a corresponding insulated electric wire 101 is electrically connected at each tip of the branch conductive path 62, a current ratio detection section 7 capable of detecting the ratio of currents flowing through the plurality of branch conductive paths 62, a current detection section 8 capable of detecting the waveform of the current flowing through the common conductive path 61 (or the current flowing through the branch conductive paths 62), a noise suppression processing section 21 that performs noise suppression processing of the ratio of the currents detected by the current ratio detection section 7 based on the current waveform detected by the current detection section 8, and a wire break detection processing section 22 that detects wire breaks in the plurality of insulated electric wires 101 based on the ratio of the currents after noise suppression processing.

[0059] With this configuration, even in the case of an early break in which the number of broken wires is small and the increase in the conductor resistance is extremely small, breaks in the wires and the progression of the break in the conductor 102 can be detected with high sensitivity based on the ratio of the currents flowing through the branch conductive paths 62. Furthermore, although the current ratio has a small signal and is easily affected by noise, in this embodiment, noise suppression processing of the current ratio is performed based on the waveforms of the currents flowing through the common conductive path 61 and the branch conductive paths 62, thereby suppressing the influence of noise and enabling more accurate detection of breaks in the wires of the conductor 102 and the progression of the break. As a result, the time to replace the cable 10 can be accurately predicted.

[0060] (Other embodiments) In the above embodiment, noise suppression processing is performed in the frequency domain using a spectrum, but noise suppression processing can also be performed in the time domain. In this case, the noise suppression processing unit 21 performs noise suppression processing by multiplying the current value detected by the current detection unit 8 by the current ratio detected by the current ratio detection unit 7. Then, the disconnection detection processing unit 22 detects a disconnection of the wire based on the average value (time average value) over a predetermined time period of the waveform obtained by multiplication in the noise suppression processing.

[0061] More specifically, as shown in FIGS. 11(a) and 11(b), the noise suppression processor 21 multiplies the total current value for the same time period by the output value of the magnetic sensor 71 to obtain a waveform that is the product of the total current value and the output value of the magnetic sensor 71. The noise suppression processor 21 then calculates the time average value of the obtained waveform for each predetermined time period. In the example shown in FIG. 11(a) where there is no wire breakage, the time average value is 0.0000004, whereas in the example shown in FIG. 11(b) where there is a wire breakage, the time average value is 0.0000566. Thus, when a wire breakage occurs, the time average value increases. Therefore, even in the case of an early wire breakage where the number of wire breakages is small and the increase in the conductor resistance is extremely small, it is possible to detect a wire breakage based on the time average value.

[0062] In order to perform the noise suppression processing in the time domain, it is necessary that there is no phase shift between the current waveform (total current waveform) detected by the current detection unit 8 and the current ratio waveform (output waveform of the magnetic sensor 71) detected by the current ratio detection unit 7. If there is a phase shift, it is advisable to provide a separate circuit or the like for adjusting the phase, or to perform noise suppression processing in the frequency domain as described in the above embodiment.

[0063] (Summary of the embodiment) Next, the technical ideas grasped from the above-described embodiments will be described by using the reference numerals and the like in the embodiments. However, the reference numerals and the like in the following description do not limit the components in the claims to the members and the like specifically shown in the embodiments.

[0064] [1] A device for detecting breaks in wires (101) of a plurality of insulated electric wires having conductors (102) each made of a plurality of wires, the device comprising a common conductive path (61) and a plurality of branch conductive paths (62) branched from the tip of the common conductive path (61), and capable of detecting the ratio of the current flowing through the branch portion (6) to the tip of each of the branch conductive paths (62) to which one end of the conductor (102) of the corresponding insulated electric wire (101) is electrically connected, and the ratio of the current flowing through the plurality of branch conductive paths (62). a current detection unit (8) capable of detecting the waveform of the current flowing in the common conductive path (61) or the current flowing in the branch conductive path (62); a noise suppression processing unit (21) that performs noise suppression processing of the ratio of the currents detected by the current ratio detection unit (7) based on the waveform of the current detected by the current detection unit (8); and a disconnection detection processing unit (22) that detects disconnection of the wires in the plurality of insulated electric wires (101) based on the ratio of the currents that have been subjected to the noise suppression processing.

[0065] [2] The disconnection detection device (1) described in [1], wherein the noise suppression processing unit (21) performs the noise suppression processing by applying the spectrum of the current detected by the current detection unit (8) as a spectrum mask to the spectrum of the current ratio.

[0066] [3] The wire break detection device (1) described in [2], wherein the wire break detection processing unit (22) selects multiple frequencies with high signal strength from the spectrum of the current ratio after the noise suppression processing, calculates the relative ratio of the signal strength at the selected frequencies, and detects a wire break when the calculated relative ratio of the signal strength is within a predetermined threshold range.

[0067] [4] The disconnection detection device (1) described in [3], wherein the predetermined threshold range is set based on the relative ratio of signal strength at the selected frequency when the spectrum mask is applied to the spectrum of the current detected by the current detection unit (8).

[0068] [5] The wire break detection device (1) described in [1], wherein the noise suppression processing unit (21) performs the noise suppression processing by multiplying the current value detected by the current detection unit (8) by the current ratio detected by the current ratio detection unit (7), and the wire break detection processing unit (22) detects a wire break based on the average value of the waveform obtained by the multiplication over a predetermined time period.

[0069] [6] The disconnection detection device (1) described in [1], wherein the other ends of the multiple insulated wires (101) are connected to the same connection destination, and the multiple insulated wires (101) and the multiple branch conductive paths (62) connected in series are connected in parallel between the connection destination and the common conductive path (61).

[0070] [7] The disconnection detection device (1) described in [1], wherein the branch section (6) has two of the branch conductive paths (62), and the current ratio detection section (7) is composed of a magnetic sensor (71) arranged between the two branch conductive paths (62).

[0071] [8] The disconnection detection device (1) according to [7], wherein the branch portion (6) is configured by a bus bar.

[0072] [9] The disconnection detection device (1) described in [8], wherein the two branch conductive paths (62) have the same shape, and the two insulated electric wires (101) connected to the two branch conductive paths (62) have the same configuration, and the magnetic sensor (71) is positioned so that its magnetic detection portion (71a) is located at a midpoint between the two branch conductive paths (62).

[0073]

[10] The disconnection detection device (1) described in [1], wherein the disconnection detection processing unit (22) detects the progress of the disconnection in the conductor (102) based on the ratio of the currents that have undergone the noise suppression processing.

[0074]

[11] A wire break detection device (1) for detecting a wire break in a plurality of insulated electric wires (101) having a conductor (102) made of a plurality of wires, the wire break detection device (1) comprising: a current ratio detection unit (7) capable of detecting a ratio of currents flowing through the plurality of insulated electric wires (101) when current from a predetermined supply source is branched and supplied to the plurality of insulated electric wires (101); a current detection unit (8) capable of detecting a waveform of the current from the supply source or the current flowing through the plurality of insulated electric wires (101); a noise suppression processing unit (21) performing noise suppression processing on the ratio of the currents detected by the current ratio detection unit (7) based on the waveform of the current detected by the current detection unit (8); and a wire break detection processing unit (22) for detecting a wire break in the plurality of insulated electric wires (101) based on the ratio of the currents after the noise suppression processing.

[0075]

[12] A method for detecting a break in a wire in a plurality of insulated wires (101) having a conductor (102) consisting of a plurality of wires, the method comprising: detecting a ratio of currents flowing through the plurality of insulated wires (101) when current from a predetermined supply source is branched and supplied to the plurality of insulated wires (101); detecting a waveform of the current from the supply source or the current flowing through the plurality of insulated wires (101); performing noise suppression processing on the detected current ratio based on the detected current waveform; and detecting a break in the wire in the plurality of insulated wires (101) based on the ratio of the currents after the noise suppression processing.

[0076]

[13] A wire break detection connector (13) used to detect a break in a wire in a plurality of insulated electric wires (101) having conductors (102) consisting of a plurality of wires, the wire break detection connector (13) having a common conductive path (61) and a plurality of branch conductive paths (62) branched from a tip of the common conductive path (61), and including a branch section (6) to which one end of the conductor (102) of a corresponding insulated electric wire (101) is electrically connected to each tip of the branch conductive path (62), a current ratio detection section (7) capable of detecting a ratio of currents flowing through the plurality of branch conductive paths (62), and a current detection section (8) capable of detecting the waveform of the current flowing through the common conductive path (61) or the branch conductive paths (62).

[0077] (Addendum) Although the embodiments of the present invention have been described above, the invention according to the claims is not limited to the above-described embodiments. It should be noted that not all of the combinations of features described in the embodiments are necessarily essential to the means for solving the problems of the invention. Furthermore, the present invention can be appropriately modified and implemented within the scope of its spirit. [Explanation of symbols]

[0078] 1...Disconnection detection device 2...Control unit 20...Data acquisition processing unit 21...Noise suppression processing unit 22...Disconnection detection processing unit 23...Cable life prediction processing unit 3...Storage section 31...Sensor output data 32...Disconnection detection data 33...Life expectancy data 6...Branch 61...Common conductive path 62...Branch conductive path 7...Current ratio detection section 71...Magnetic sensor 71a...magnetic detection unit 8...Current detection section 10...Cable 101...Insulated wire 102...conductor 103...Insulator 104...Sheath 13...Connector (connector for detecting disconnection) 131...Circuit board

Claims

1. 1. A device for detecting breaks in wires in a plurality of insulated electric wires having conductors each made of a plurality of wires, comprising: a branch portion including a common conductive path and a plurality of branch conductive paths branching from a tip end of the common conductive path, and one end of the conductor of the corresponding insulated electric wire is electrically connected to each tip end of the branch conductive path; a current ratio detection unit capable of detecting a ratio of currents flowing through the plurality of branch conduction paths; a current detection unit capable of detecting a waveform of a current flowing through the common conductive path or a waveform of a current flowing through the branch conductive path; a noise suppression processing unit that performs noise suppression processing of the current ratio detected by the current ratio detection unit based on the waveform of the current detected by the current detection unit; and a wire breakage detection processing unit that detects a wire breakage in the plurality of insulated wires based on a ratio of the currents that have been subjected to the noise suppression processing. Disconnection detection device.

2. the noise suppression processing unit performs the noise suppression processing by applying the spectrum of the current detected by the current detection unit as a spectrum mask to the spectrum of the current ratio. The wire break detection device according to claim 1 .

3. the disconnection detection processing unit selects a plurality of frequencies with high signal strength from the spectrum of the current ratio after the noise suppression processing, calculates a relative ratio of the signal strengths at the selected frequencies, and detects a disconnection of the wire when the calculated relative ratio of the signal strengths is within a predetermined threshold range. The wire breakage detection device according to claim 2 .

4. the predetermined threshold range is set based on a relative ratio of signal strengths at the selected frequencies when the spectrum mask is applied to the spectrum of the current detected by the current detection unit. The wire breakage detection device according to claim 3 .

5. the noise suppression processing unit performs the noise suppression processing by multiplying the waveform of the current detected by the current detection unit by the waveform of the current ratio detected by the current ratio detection unit; The disconnection detection processing unit detects a disconnection of the wire based on an average value of the waveform obtained by the multiplication over a predetermined time period. The wire break detection device according to claim 1 .

6. The other ends of the plurality of insulated wires are connected to the same connection destination, a plurality of the insulated wires and the branch conductive paths connected in series are connected in parallel between the connection destination and the common conductive path; The wire break detection device according to claim 1 .

7. the branch portion has two of the branch conductive paths, the current ratio detection unit is composed of a magnetic sensor disposed between the two branched conductive paths; The wire break detection device according to claim 1 .

8. The branch portion is configured by a bus bar. The wire break detection device according to claim 7.

9. the two branch conductive paths have the same shape, and the two insulated wires connected to the two branch conductive paths have the same configuration; the magnetic sensor is disposed so that its magnetic detection portion is located at a midpoint between the two branched conductive paths; The wire breakage detection device according to claim 8.

10. the disconnection detection processing unit detects the progress of the disconnection of the conductor based on the ratio of the currents that have been subjected to the noise suppression processing. The wire break detection device according to claim 1 .

11. 1. A device for detecting breaks in wires in a plurality of insulated electric wires having conductors each made of a plurality of wires, comprising: a current ratio detection unit capable of detecting a ratio of currents flowing through the plurality of insulated wires when currents from a predetermined supply source are split and supplied to the plurality of insulated wires; a current detection unit capable of detecting a waveform of a current from the supply source or a current flowing through the plurality of insulated electric wires; a noise suppression processing unit that performs noise suppression processing of the current ratio detected by the current ratio detection unit based on the waveform of the current detected by the current detection unit; and a wire breakage detection processing unit that detects a wire breakage in the plurality of insulated wires based on a ratio of the currents that have been subjected to the noise suppression processing. Disconnection detection device.

12. A method for detecting breaks in wires in a plurality of insulated electric wires having conductors each made of a plurality of wires, the method comprising: detecting a ratio of currents flowing through the plurality of insulated wires when currents from a predetermined supply source are split and supplied to the plurality of insulated wires; Detecting a waveform of a current from the supply source or a current flowing through the plurality of insulated electric wires, and performing noise suppression processing for a ratio of the detected currents based on the detected current waveforms; detecting a break in the wires of the plurality of insulated wires based on a ratio of the currents subjected to the noise suppression process; Disconnection detection method.

13. A connector used to detect breaks in a plurality of wires in an insulated electric wire having a conductor made of a plurality of wires, a branch portion including a common conductive path and a plurality of branch conductive paths branching from a tip end of the common conductive path, and one end of the conductor of the corresponding insulated electric wire is electrically connected to each tip end of the branch conductive path; a current ratio detection unit capable of detecting a ratio of currents flowing through the plurality of branch conduction paths; a current detection unit capable of detecting a waveform of a current flowing through the common conductive path or a waveform of a current flowing through the branch conductive path; Connector for detecting broken wires.

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